KR20220097266A - Compositions for depositing material, synthesis methods and uses - Google Patents

Abstract

The present disclosure relates to a composition for depositing a group 13 metal-containing material on a substrate. The composition includes a metal alkyl precursor, wherein the metal alkyl precursor includes one group 13 metal atom and two different types of alkyl ligands. The first ligand type is a branched C4 to C8 alkyl bonded to the group 13 metal atom through a carbon atom bonded to three carbon atoms, and the second ligand type is a linear C1 to C4 alkyl. The group 13 metal atom is bound to two ligands of the first ligand type, and the ratio of the first ligand type to the second ligand type in the composition is about 2 to 1. The present disclosure also relates to a method of depositing a material onto a substrate, as well as a method of making the composition and the use thereof.

Description

COMPOSITIONS FOR DEPOSITING MATERIAL, SYNTHESIS METHODS AND USES

The present disclosure relates generally to a composition for depositing a metal precursor to form a metal-containing layer on a substrate. The present disclosure also relates to methods of making the compositions and uses thereof, as well as methods of depositing materials on substrates.

Group 13 metals, in particular aluminum, gallium and indium, are used in a variety of applications for the production of semiconductor devices. One example is a metal-containing thin film for work function tuning applications. Selection of a suitable metal precursor compound is critical to successful deposition and material performance. These metal compounds require a specific combination of physical and chemical properties so that they are useful in producing films with the desired composition, resistivity, and effective work function.

Alkyl metal compounds are attractive precursors for vapor deposition. However, to find suitable precursors, it is difficult to have the right combination of volatility, reactivity and stability for use in demanding deposition applications. Accordingly, there is a need in the art for improved metal precursors for depositing thin films for the fabrication of semiconductor devices.

The present invention describes metal precursor compositions and methods of making them. In a first aspect, a composition for depositing a Group 13 metal containing material on a substrate is disclosed. The composition comprises a metal alkyl precursor comprising one Group 13 metal atom and two different alkyl ligand types. The first ligand type is a branched C4 to C8 alkyl bonded to a Group 13 metal atom through a carbon atom which is bonded to three carbon atoms, the second ligand type is a linear C1 to C4 alkyl, wherein the Group 13 metal atom is It binds to two ligands of a first ligand type. In a composition according to the present disclosure, the ratio of the first ligand type to the second ligand type is about 2 to 1.

In a second aspect, a method for preparing a composition according to the present disclosure is disclosed, the method comprising reacting bis(methyl) tert -butylaluminum with aluminum trichloride and tert -butyllithium to bis( tert -butyl)methylaluminum including the steps of obtaining

In a third aspect, a method for preparing a composition according to the present disclosure is disclosed, the method comprising reacting trimethylaluminum with aluminum trichloride and tert -butyllithium to obtain bis( tert -butyl)methylaluminum .

In a fourth aspect, there is provided a method for preparing a composition according to the present disclosure, the method comprising reacting tri( tert -butyl)aluminum with trimethylaluminum to obtain bis( tert -butyl)methylaluminum.

In a fifth aspect, a method of depositing a Group 13 metal containing material on a substrate using a composition according to the present disclosure is disclosed.

In a sixth aspect, the use of a composition according to the present disclosure for depositing a group 13 metal containing material on a substrate is disclosed.

In a seventh aspect, a chemical reactant container containing a composition according to the present disclosure is disclosed.

In an eighth aspect, an ac vapor deposition assembly comprising a reactant vessel according to the present disclosure is disclosed.

Mixed alkyl compounds of metals are used as precursors for semiconductor applications. They may be more stable than some of the homoleptic metal alkyl precursors, while having sufficient reactivity for sensitive deposition applications. However, different ligands are often sensitive to ligand redistribution reactions, preventing the use of mixed ligand compounds as precursors in demanding applications. Compositions according to the present disclosure can provide stability against ligand redistribution observed in other mixed alkyl metal compounds. This redistribution observed in many mixed ligand alkyl precursors can lead to the formation of a number of undesirable by-products under dynamic evaporation conditions typical for gas phase precursor delivery from condensed phase source compounds. Because these by-products differ in volatility, their relative concentrations in the precursor source vessel can vary significantly over time, often subject to substantial process drift.

The present disclosure provides compositions having unexpected stability against isomerization reactions common to, for example, metal complexes containing bulk alkyl ligands containing branched alkyl groups. Both of these types of stability can improve the vapor deposition properties of a composition according to the present disclosure. In addition, stability can promote atomic layer deposition (ALD) type growth of desired films, with reduced self-degradation, increased metal incorporation, and reduced process drift.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the disclosure and to constitute a part of this specification, illustrate exemplary embodiments and, together with the description, serve to explain the principles of the disclosure. in drawing,
1 shows a chemical reactant vessel according to the present disclosure.
2 shows a vapor deposition assembly comprising a reactant vessel according to the present disclosure.

The descriptions of examples of implementations of the compositions, methods, and uses provided below are illustrative only and are intended for illustrative purposes only. The following description is not intended to limit the scope or claims of the present disclosure. Moreover, the recitation of multiple embodiments in which a feature is described is not intended to exclude other embodiments having additional features or other embodiments, including other combinations of the specified features. For example, various embodiments are set forth as exemplary embodiments and may be recited in the dependent claims. Unless otherwise stated, exemplary embodiments or components thereof may be combined or applied separately from one another.

In this disclosure, any two values of a variable may constitute feasible ranges for that variable, and any range indicated may include or exclude endpoints. Additionally, any value of a variable indicated (whether or not indicated as “about”) may refer to an exact or approximate value and may include equivalents, mean, median, representative, majority, etc. can be referred to Also, in this disclosure, the terms “comprising,” “consisting of,” and “having” independently refer to “including, usually or approximately,” or “comprising.” In this disclosure, arbitrarily defined meanings do not necessarily exclude ordinary and customary meanings in some embodiments.

In one aspect, a composition for depositing a Group 13 metal containing material on a substrate is disclosed. The composition comprises a metal alkyl precursor, wherein the metal alkyl precursor comprises one Group 13 metal atom and two different types of alkyl ligands. The first type of ligand is a branched C4 to C8 alkyl bonded to a Group 13 metal atom through a carbon atom that is bonded to three carbon atoms. The second ligand type is a linear C1 to C4 alkyl. The Group 13 metal atom is bound to two ligands of a first ligand type, and the ratio of the first ligand type to the second ligand type in the composition is about 2 to 1. However, in some embodiments, a composition according to the present disclosure may be used to deposit a carbon-containing material on a substrate.

By composition herein is meant the preparation of a chemical that can be used in vapor deposition applications. In general, the composition needs to be sufficiently stable for storage and use over a long period of time, for example, over several months. The precursor must withstand the deposition conditions to deliver the vapor into the reaction chamber. In addition, the evaporation rate of the precursor compound under certain conditions is preferably kept constant. Some compositions may undergo one or more substances to evaporate from the composition. If the materials are of different volatility, the composition may be enriched over time with less volatile materials. This can lead to a phenomenon called process drift: one or more deposition process parameters change gradually over time as the chemical composition of the composition changes. The consequences of process drift can be detrimental in sensitive applications, and tuning the process to compensate for drift can be expensive, difficult, or even impossible. In addition, the composition needs to allow evaporation of the precursor molecules so that the precursor molecules can be delivered to a deposition chamber for vapor deposition. Therefore, the temperature and pressure ranges of the precursors contained in the composition must be suitable for vapor deposition.

The terms “precursor” and “reactant” are used interchangeably in this disclosure and may refer to a molecule (a compound or molecule comprising a single element) that participates in a chemical reaction to yield another compound. A precursor or reactant typically contains a moiety that at least partially forms a compound or element resulting from the chemical reaction in question. This final compound or element may be deposited on a substrate. However, a precursor or reactant may be an element or compound that is not incorporated into the final compound or element to a significant extent. In some embodiments, the reactant or precursor may be a reducing agent.

A composition according to the present disclosure includes a metal alkyl precursor comprising a Group 13 metal atom. In some embodiments, the Group 13 metal is selected from the group consisting of aluminum, gallium, and indium. In some embodiments, the Group 13 metal is aluminum. In some embodiments, the Group 13 metal is gallium. In some embodiments, the Group 13 metal is indium.

Metal alkyl precursors according to the present disclosure comprise two different alkyl ligand types, a first ligand type and a second ligand type. Thus, each Group 13 metal atom is bound to two different types of ligands.

The first type of ligand is a branched C4 to C8 alkyl bonded to a Group 13 metal atom through a carbon atom that is bonded to three carbon atoms. That is, a Group 13 metal atom is attached to a carbon atom, which in turn is attached to three carbon atoms (three "branched carbon atoms"). These alkyl ligands occupy large spaces around metal atoms, can create steric effects on the reaction, and the spatial orientation of the atoms can also affect bond strength. The first type of ligand is an alkyl group containing 4 to 8 carbon atoms, ie C4 to C8 alkyl. Thus, it may contain 4, 5, 6, 7 or 8 carbon atoms. Since the carbon atom that is bound to the metal atom is linked to three other carbon atoms, the smallest ligand of the first ligand type is a tert -butyl group. In some embodiments, the first ligand type is tert -butyl.

Any of the three branching carbon atoms may have one or more additional carbon atoms attached thereto. Often, there is one or two additional carbon atoms attached to the branching carbon atom. In some embodiments, one or two of the three branching carbon atoms have one or more additional carbon atoms attached thereto. In some embodiments, all three of the branching carbon atoms have an additional carbon atom attached thereto. In some embodiments, the first ligand type is C4 or C5 alkyl. In this embodiment, one of the branching carbon atoms has one additional carbon atom attached thereto. In some embodiments, the first ligand type is C4 to C6 alkyl. In such embodiments, one branching carbon atom may have two additional carbon atoms attached thereto. Alternatively, two of the branched carbon atoms may have one additional carbon atom attached to each branched carbon atom.

A group 13 metal atom is bound to two ligands of the first ligand type. In some embodiments, both ligands of the first ligand type are the same. Having two identical ligands of the first ligand type can simplify the precursor synthesis process as compared to having two different ligands of the first ligand type in the metal alkyl precursor.

In some embodiments, the first ligand type is a saturated hydrocarbon. In some embodiments, the second ligand type is a saturated hydrocarbon. In some embodiments, the first ligand type and the second ligand type are saturated hydrocarbons. In some embodiments, the first ligand type may comprise one or more double bonds. In some embodiments, two ligands of the first ligand type form a metal containing ring substituted with a Group 13 metal atom. The metal containing ring can be, for example, a substituted metal containing cyclobutane, a substituted metal containing cyclopentane or a substituted metal containing cyclohexane.

The second ligand type is a linear C1 to C4 alkyl. Thus, the second ligand type is smaller than the first ligand type. In some embodiments, the second ligand type is methyl or ethyl. In some embodiments, the second ligand is propyl. In some embodiments, the second ligand type is butyl. In the composition of claim 1, said first ligand type is tert -butyl and said second ligand type is methyl. In some embodiments, the first ligand type is tert -butyl and the second ligand type is ethyl. In some embodiments, the first ligand type is tert -butyl and the second ligand type is propyl.

In some embodiments, the first ligand type is 1,1-dimethylpropyl and the second ligand type is methyl. In some embodiments, the first ligand type is 1,1-dimethylpropyl and the second ligand type is ethyl. In some embodiments, the first ligand type is 1,1-dimethylpropyl and the second ligand type is propyl. In some embodiments, the first ligand type is 1,1-dimethylpropyl and the second ligand type is butyl.

In some embodiments, the first ligand type is 1-ethyl-1-methylpropyl and the second ligand type is methyl. In some embodiments, the first ligand type is 1-ethyl-1-methylpropyl and the second ligand type is ethyl. In some embodiments, the first ligand type is 1-ethyl-1-methylpropyl and the second ligand type is propyl. In some embodiments, the first ligand type is 1-ethyl-1-methylpropyl and the second ligand type is butyl.

In some embodiments, the first ligand type is 1,1-diethylpropyl and the second ligand type is methyl. In some embodiments, the first ligand type is 1,1-diethylpropyl and the second ligand type is ethyl. In some embodiments, the first ligand type is 1,1-diethylpropyl and the second ligand type is propyl. In some embodiments, the first ligand type is 1,1-diethylpropyl and the second ligand type is butyl.

In a composition according to the present disclosure, the ratio of the first ligand type to the second ligand type in the composition is about 2 to 1. Thus, for each Group 13 metal atom, there are approximately two ligands in the first ligand group, and one ligand in the second ligand group.

In some embodiments, the second ligand type can be hydrogen. Accordingly, a composition for depositing a Group 13 metal-containing material on a substrate according to the present disclosure may comprise a metal alkyl precursor, wherein the metal alkyl precursor comprises one Group 13 metal atom and two different alkyl ligand types; , wherein the first ligand type is a branched C4 to C8 alkyl bonded to a Group 13 metal atom through a carbon atom bonded to three carbon atoms, and the second ligand type is hydrogen. In the composition, the Group 13 metal atom is bound to two ligands of a first ligand type, and the ratio of the first ligand type to the second ligand type in the composition is about 2 to 1.

A metal alkyl precursor according to the present disclosure may exist as a monomer (shown below as Structure 1) or as a dimer (shown as Structure 2 below). In the structure, L1 represents a first ligand type and L2 represents a second ligand type. In the solid composition, the metal alkyl precursor may be present primarily as a dimer. In the gas, the metal alkyl precursor can be freely exchanged between the monomer and the dimer, leading to a mixture of both forms. Thus, in the gas phase, the metal alkyl precursor may exist as a mixture of dimers and monomers. The monomeric form may predominate in the gas phase.

As visualized below, in both forms, each Group 13 metal atom is bound to two ligands of type 1, and the ratio of the first ligand type to the second ligand type is 2 to 1. However, in dimers, a Group 13 metal atom is linked to two ligands of a second ligand type. In this configuration, the second ligand type can be characterized as a bridging ligand. Without limiting the present disclosure to any particular theory of the structure of the metal alkyl precursor, the ML ₂ -M unit may be described as a three-centered two-electron bond.

Without limiting the present disclosure to any particular theory, the dimers may be particularly stable, making solid compositions comprising metal alkyl precursors according to the present disclosure advantageous for vapor deposition processes. In some embodiments, at least 50% of the metal alkyl precursor is present as dimers in the solids composition.

The metal alkyl precursor may be a precursor in a vapor deposition process. Thus, a composition according to the present disclosure can be used to deposit a Group 13 metal - either as a metallic metal or as a compound with another element - on a substrate.

The vapor deposition process according to the present disclosure may be a chemical vapor deposition (CVD) process. The vapor deposition process according to the present disclosure may be an atomic layer deposition (ALD) process. The vapor deposition process according to the present disclosure may be a periodic vapor deposition process. As used herein, the term “periodic deposition” may refer to depositing a layer on a substrate by sequential introduction of precursors (reactants) into a reaction chamber and process techniques such as atomic layer deposition and periodic chemical vapor deposition. includes

CVD type processes generally involve a gas phase reaction between two or more precursors or reactants. The precursor or reactant may be provided simultaneously, partially, or completely separate pulses to the reaction space or substrate. The substrate and/or reaction space may be heated to promote reaction between the gaseous reactants. In some embodiments, a reactant is provided until a thin film having a desired thickness is deposited. Thus, a CVD type process may be a periodic process or an aperiodic process. In some embodiments, a cyclic CVD-type process may be used with multiple cycles to deposit a thin film having a desired thickness. In a periodic CVD-type process, reactants may be provided to the reaction chamber in pulses that do not overlap, partially overlap, or fully overlap.

ALD type processes are based on controlled, in particular self-limiting surface reactions of precursor and/or reactant chemicals. Gas phase reactions are prevented by providing the precursors alternately and sequentially within the reaction chamber. Gas phase reactants are separated from each other in the reaction chamber, for example by removing excess reactants and/or reaction byproducts from the reaction chamber between reactant pulses. This may be accomplished via an evacuation stage and/or by an inert gas pulse or purge. In some embodiments, the substrate is contacted with a purge gas, such as an inert gas. For example, the substrate may be contacted with a purge gas between reaction pulses to remove excess reactants and reaction byproducts. In some embodiments each reaction is self-limiting, and monolayers are achieved by monolayer growth. These may be referred to as “real ALD” reactions. In some such embodiments, the metal precursor may be adsorbed to the substrate surface in a self-controlled manner. The second reactant precursor or reactant, and any additional reactant or precursor, in turn react with the adsorbed metal precursor to form even a monolayer of the metal or metal compound on the substrate.

A composition according to the present disclosure may be used to deposit a Group 13 metal-containing material on a substrate. As used herein, the term “substrate” may refer to any underlying material or materials that may be used to form, or upon which a structure, device, circuit, or layer may be formed. The substrate may comprise a bulk material, such as silicon (eg, single crystal silicon), another group IV material, such as germanium, or another semiconductor material, such as a group II-VI or group III-V semiconductor material, overlying or It may include one or more layers underlying it. In addition, the substrate may include various features formed in or over at least a portion of the layers of the substrate, such as recesses, protrusions, and the like. For example, the substrate may include a bulk semiconductor material and a layer of insulating or dielectric material overlying at least a portion of the bulk semiconductor material.

The Group 13 metal containing material may be deposited as a layer or thin film. As used herein, the terms “layer” and/or “film” may refer to any continuous or discontinuous structure and material, such as a material deposited by a vapor deposition process described herein. For example, layers and/or films may comprise two-dimensional materials, three-dimensional materials, nanoparticles or even partial or entire molecular layers or partial or entire atomic layers or atoms and/or molecular clusters. The film or layer may comprise a material or layer having pinholes, which may be at least partially continuous. The layer may be a seed layer. The seed layer may be a discontinuous layer that acts to increase the nucleation rate of other materials. However, the seed layer may also be substantially or completely continuous.

The group 13 metal-containing material may be a metallic (elemental) metal such as aluminum metal, indium metal or gallium metal. In some embodiments, the Group 13 metal is selected from the group consisting of aluminum, gallium, and indium. Therefore, the oxidation state of the metal may be zero. In some embodiments, the oxidation state of the metal is non-zero. In some embodiments, the oxidation state can be, for example, +1 or +3. The deposited material, or a layer comprising the deposited material, may include other elements or compounds upon which a metal is deposited from a composition according to the present disclosure. In some embodiments, a Group 13 metal may be deposited to obtain a metal carbide, nitride, or oxide. For example, aluminum oxide, aluminum carbide or aluminum nitride, gallium oxide, gallium carbide or gallium nitride, indium oxide, indium carbide or indium nitride may be deposited. The present compositions can also be used to deposit ternary materials, including Group 13 metals, along with, for example, silicon and oxides. Compositions according to the present disclosure may also be used to deposit metal alloys such as cobalt-aluminum, ruthenium-aluminum, molybdenum-aluminum or tungsten-aluminum.

A composition according to the present disclosure comprises a Group 13 metal having two ligands of a first ligand type and one ligand of a second ligand type attached thereto. Metal alkyl compounds containing more than one ligand type (ie mixed-alkyl metal compounds) are often susceptible to ligand redistribution, which can lead to the formation of various unwanted byproducts in vapor deposition. Under these conditions, the most volatile materials evaporate preferentially, resulting in process drift during use of a given batch of precursors. That is, advantageous compositions retain their uniformity over a long period of time on the tool. It was unexpectedly found that ligand configurations according to the present disclosure have significantly reduced redistribution tendencies compared to other metal alkyl compounds of similar structure.

In addition, precursor compounds having the ligand configurations described herein are more stable than expected against isomerization reactions common to metal complexes containing bulk alkyl ligands such as tert -butyl groups. Stability of precursor compounds according to the present disclosure may increase precursor shelf life at evaporation temperatures, on-tool stability, as well as increase reduction in decomposition during vapor deposition. In particular, stability during deposition can be important in atomic layer deposition type processes that target self-limited growth of the deposited material.

As a further advantage of the compositions according to the present disclosure, they can have a sufficiently high vapor pressure to be used with suitable heating. This allows their use in vapor deposition processes with limited thermal budgets.

In some embodiments, a composition according to the present disclosure comprises at least 80 w-% of a metal alkyl precursor. In some embodiments, a composition according to the present disclosure comprises at least 90 w-% of a metal alkyl precursor. In some embodiments, a composition according to the present disclosure comprises at least 92 w-% of a metal alkyl precursor. In some embodiments, a composition according to the present disclosure comprises at least 95 w-% of a metal alkyl precursor. In some embodiments, a composition according to the present disclosure comprises at least 98 w-% of a metal alkyl precursor. In some embodiments, a composition according to the present disclosure consists essentially of a metal alkyl precursor. In some embodiments, a composition according to the present disclosure consists of a metal alkyl precursor. Accordingly, a composition according to the present disclosure may contain at least 80 w-%, at least 85 w-%, at least 90 w-%, at least 92 w-%, at least 95 w-% or at least 98 w-% bis( tert -butyl) Methyl aluminum may be included. In some embodiments, a composition according to the present disclosure comprises at least 80 w-%, at least 85 w-%, at least 90 w-%, at least 92 w-%, at least 95 w-% or at least 98 w-% bis( turt ) -Butyl) contains methylgallium. In some embodiments, a composition according to the present disclosure comprises at least 80 w-%, at least 85 w-%, at least 90 w-%, at least 92 w-%, at least 95 w-% or at least 98 w-% bis( turt ) -Butyl) methylindium may be included.

The compositions used for semiconductor applications are preferentially pure to assure the reproducibility, transferability and scalability of the deposition process. In some embodiments, the composition may contain a related compound of a metal alkyl precursor, such as a compound comprising three ligands of a first ligand type or two ligands of a second ligand type. The composition may also include a compound derived from isomerization of a ligand of a first ligand type.

The purity of a composition according to the present disclosure can be measured, for example, by the ratio of the first and second ligand type ligands. In a composition comprising only the target metal alkyl precursor, the ratio of ligands of the first ligand type to the second ligand type, for example the ratio of tert -butyl to methyl, will be two. In some embodiments, the ratio of the first ligand type ligand to the second ligand type ligand is about 1.90, about 1.95, about 1.99, about 2.05, or about 2.10. In some embodiments, the ratio of the first ligand type ligand to the second ligand type ligand is between about 1.90 and 2.05. In some embodiments, the ratio is between about 1.95 and 2.10. In some embodiments, the ratio of the first ligand type ligand to the second ligand type ligand is between about 1.95 and 2.05.

In some embodiments, compositions according to the present disclosure include up to 10 w-% of materials other than metal alkyl precursors. In some embodiments, compositions according to the present disclosure include up to 8 w-% of materials other than metal alkyl precursors. In some embodiments, compositions according to the present disclosure include up to 5 w-% of materials other than metal alkyl precursors. In some embodiments, compositions according to the present disclosure include up to 2 w-% of materials other than metal alkyl precursors. In some embodiments, the amount of material other than the metal alkyl precursor is below the detection limit of NMR spectroscopy.

In some embodiments, the vapor pressure of a composition according to the present disclosure is at least about 1 Torr at a temperature of at least 20°C. In some embodiments, the vapor pressure of the composition may be at least about 1 Torr at a temperature of at least 50°C. In some embodiments, the vapor pressure of the composition may be at least about 1 Torr at a temperature of at least 60°C. In some embodiments, the vapor pressure of the composition may be at least about 1 Torr at a temperature of at least 70°C. In some embodiments, the vapor pressure of the composition may be at least about 1 Torr at a temperature of at least 100°C. In some embodiments, the vapor pressure of the composition may be at least about 1 Torr at a temperature of at least 120°C. In some embodiments, the vapor pressure of the composition may be at least about 1 Torr at a temperature of at least 150°C. In some embodiments, the vapor pressure of the composition may be at least about 1 Torr at a temperature of at least 180°C.

For example, in some embodiments, the vapor pressure of a composition according to the present disclosure is at least about 1 Torr at a temperature between 20°C and 50°C. In some embodiments, the vapor pressure of a composition according to the present disclosure is at least about 1 Torr at a temperature between 50°C and 100°C. In some embodiments, the vapor pressure of a composition according to the present disclosure is at least about 1 Torr at a temperature between 70°C and 150°C. In some embodiments, the vapor pressure of a composition according to the present disclosure is at least about 1 Torr at a temperature between 100°C and 170°C.

In some embodiments, the vapor pressure of the composition is about 1 Torr at a temperature of 65°C. In some embodiments, the vapor pressure of the composition is about 10 Torr at 90°C. In some embodiments, the vapor pressure of the composition is about 1 Torr at a temperature of 64 to 69 °C. In some embodiments, the vapor pressure of the composition is about 3 Torr at a temperature of 70 to 74 °C. In some embodiments, the vapor pressure of the composition is about 5 Torr at a temperature of 75 to 79 °C. In some embodiments, the vapor pressure of the composition is about 7 Torr at a temperature of 80°C to 84°C.

The stability of a composition according to the present disclosure can be measured, for example, by determining a ¹ H NMR spectrum of a sample that can be used to detect ligand isomerization. In some embodiments, a composition according to the present disclosure is stable at a temperature of 62°C for at least 10 weeks.

In some embodiments, the composition may be solid at standard temperature and pressure. In some embodiments, the composition is solid at ambient pressure at a temperature of less than 120 °C. Thus, for vapor deposition processes, the composition according to the present disclosure can be used as a solid composition. Without limiting the present disclosure to any particular theory, the stability of the composition may be attributable, at least in part, to the solid form of the composition. The relatively high vapor pressure and stability also allow the use of current compositions in a variety of processes when low deposition temperatures are required. Accordingly, in some embodiments, a composition according to the present disclosure is suitable for depositing a Group 13 metal containing material onto a substrate by a vapor deposition process. In some embodiments, the aluminum containing material is deposited. In some embodiments, the gallium containing material is deposited. In some embodiments, the indium containing material is deposited.

In one aspect, the present disclosure relates to a method for preparing a composition according to the present disclosure. The method comprises reacting bis(methyl) tert -butylaluminum with aluminum trichloride and tert -butyllithium as described below to obtain bis( tert -butyl)methylaluminum. In some embodiments, bis(methyl) tert -butylaluminum is reacted with aluminum trichloride and tert -butyllithium in a molar ratio of 1:1:3. This reaction can proceed by transferring a tert -butyl group from lithium to aluminum trichloride, removing the chloride induced by the formation of lithium chloride as a readily removed byproduct. The alkyl ligand exchange reaction between the bis(methyl) tert -butylaluminum starting material and the newly formed tert-butyl bearing aluminum species can produce the target molecule in high yield. The yield may vary depending on the ratio of the reactants, which may be controlled by methods known in the art.

In some embodiments, a method of preparing a composition according to the present disclosure comprises purifying bis( tert -butyl)methylaluminum from a reaction mixture. Bis( tert -butyl)methylaluminum can be purified by filtration to remove aluminum trichloride. Bis( tert -butyl)methylaluminum can be purified by fractional sublimation. In this method, the solvent used in the reaction may first be evaporated. Next, bis( tert -butyl)methylaluminum can be collected on the condenser of the sublimation apparatus leaving the nonvolatile component as a residual fraction. Alternatively or additionally, salts such as chloride may be removed from the reaction mixture by filtration.

In one aspect, a method of preparing a composition according to the present disclosure comprising reacting tri( tert -butyl)aluminum with trimethylaluminum to obtain bis( tert -butyl)methylaluminum is disclosed.

In another aspect, a method for preparing a composition according to the present disclosure comprising reacting trimethylaluminum with aluminum trichloride and tert -butyllithium to obtain bis( tert -butyl)methylaluminum is disclosed.

In another aspect, a method of depositing a Group 13 metal containing material on a substrate using a composition according to the present disclosure is disclosed. In some embodiments, the Group 13 metal-containing material is deposited by a vapor deposition process. The vapor deposition process may be a periodic vapor deposition process, such as an ALD or periodic CVD process. A method of depositing a Group 13 metal-containing material on a substrate includes providing a substrate into a reaction chamber, providing a composition according to the present disclosure in a vapor phase into the reaction chamber; and providing the second reactant in a vapor phase into the reaction chamber to form a group 13 metal-containing material on the substrate. As mentioned above, the material may be, for example, an aluminum-, indium- or gallium-containing material.

In some embodiments of the method, the Group 13 metal deposited on the substrate is selected from the group consisting of aluminum, gallium and indium. In some embodiments, the aluminum containing material is deposited. In some embodiments, the gallium containing material is deposited. In some embodiments, the indium containing material is deposited.

Accordingly, in one aspect, a composition according to the present disclosure for use in a vapor deposition process is disclosed. In a sixth aspect, the use of a composition according to the present disclosure for depositing a group 13 metal containing material on a substrate is disclosed.

The chemical composition of the deposited metal-containing material will be affected by the second reactant. Accordingly, the second reactant will be selected according to the application in question. The specific deposition conditions may vary depending on the application in question. In some embodiments, a method of depositing a Group 13 metal-containing material comprises pulsing a composition according to the present disclosure into a reaction chamber. In some embodiments, the method comprises pulsing a second reactant into the reaction chamber. In some embodiments, the method comprises purging the reaction chamber between reactant pulses.

As used herein, the term “purge” may refer to a procedure in which an inert or substantially inert gas is provided to a reactor chamber between two gas pulses that react with each other. However, the purge can be made between two pulses of gas that do not react with each other. For example, it may be purged by using nitrogen gas, or provided between pulses of two precursors or between a precursor and a reducing agent. Purge may avoid or at least reduce gas phase interactions between two gases reacting with each other. It should be understood that spreading can affect time or space, or both. For example, in the case of a temporal purge, the purge step may be, for example, a temporal sequence of providing a first precursor to the reactor chamber, providing a purge gas to the reactor chamber, and providing a second precursor to the reactor chamber. , where the substrate on which the layer is deposited does not move. For example, in the case of a spatial purge, the purge step may take the form: moving the substrate from a first position to which a first precursor is continuously supplied to a second position where a second precursor is continuously supplied through a purge gas curtain steps can be taken to

A method of depositing a group 13 containing material in accordance with the present disclosure includes providing a substrate in a reaction chamber. That is, the substrate is introduced into a space in which deposition conditions can be controlled. The reaction chamber may be part of a cluster tool where different processes are performed to form the integrated circuit. In some embodiments, the reaction chamber can be a flow reactor, such as a cross flow reactor. In some embodiments, the reaction chamber may be a showerhead reactor. In some embodiments, the reaction chamber may be a space partitioning reactor. In some embodiments, the reaction chamber may be a single wafer ALD reactor. In some embodiments, the reaction chamber may be a high capacity production single wafer ALD reactor. In some embodiments, the reaction chamber may be a batch reactor for producing multiple substrates simultaneously.

In one aspect, a reactant vessel containing a composition according to the present disclosure is disclosed. A chemical reactant delivery system for vapor deposition may include a reactant vessel for providing a reactant within a reaction chamber. The reactant delivery system may include heating means including heaters such as radiant heat lamps, resistive heaters, and the like. In some embodiments, the heating means may be adapted to heat the reactant vessel to a temperature of from about 40 °C to about 140 °C, such as to about 70 °C, 85 °C, 90 °C, 110 °C or 120 °C. can In some embodiments, the heating means may be adapted to heat the reactant vessel to a temperature between about 50°C and about 140°C. In some embodiments, the heating means may be configured to heat the reactant vessel to a temperature between about 60°C and about 140°C. In some embodiments, the heating means may be configured to heat the reactant vessel to a temperature between about 80°C and about 140°C. In some embodiments, the heating means can be adapted to heat the reactant vessel to a temperature between about 100°C and about 140°C. In some embodiments, the heating means can be adapted to heat the reactant vessel to a temperature between about 40°C and about 120°C. In some embodiments, the heating means may be adapted to heat the reactant vessel to a temperature between about 40°C and about 100°C. In some embodiments, the heating means can be adapted to heat the reactant vessel to a temperature between about 40°C and about 80°C. In some embodiments, the heating means may be adapted to heat the reactant vessel to a temperature between about 40°C and about 70°C.

The reactant vessel contains a solids composition according to the present disclosure. The heater heats the reactant vessel to evaporate the reactants in the reactant vessel. The reactant vessel may have an inlet and an outlet to allow a carrier gas (eg, N ₂ ) to flow through the reactant vessel. The carrier gas may be an inert gas. The carrier gas sweeps the reactant vapor, eg, the sublimated reactant, together with the carrier gas through the reactant vessel outlet and finally to the substrate in the reaction chamber. The reactant vessel typically includes an isolation valve for fluidly isolating the contents of the reactant vessel from outside the vessel. One isolation valve may be provided upstream of the reactant vessel inlet and another shutoff valve may be provided downstream of the reactant vessel outlet.

Compositions according to the present disclosure may be solid at standard pressure and temperature. Depending on the application, the composition may be heated and/or maintained at very low pressures to generate sufficient amounts of reactant vapors for vapor deposition processes. Once evaporated (eg, sublimed), the gaseous reactants are maintained at or above the evaporation temperature through the processing system, preferably in valves, filters, conduits and other components associated with delivering the gaseous reactants into the reaction chamber. It is important to prevent undesired condensation.

The reactant vessel is supplied with gas lines extending from the inlet and outlet, an isolation valve on the line, and a fitting on the valve, the fitting configured to connect to a gas flow line of the remainder of the vapor deposition assembly. To prevent the reactant vapors from condensing and depositing on these components, it is usually desirable to provide a number of additional heaters for heating the various valves and gas flow lines between the reactant vessel and the reaction chamber. Accordingly, the gas delivery component between the reactant vessel and the reaction chamber is often referred to as a "hot zone" in which the temperature is maintained above the vaporization/condensation/sublimation temperature of the reactants.

In some embodiments, a reactant vessel according to the present disclosure is constructed and arranged for use in a vapor deposition assembly. In some embodiments, a reactant vessel according to the present disclosure contains bis( tert -butyl)methylaluminum. In some embodiments, a chemical reactant vessel according to the present disclosure contains bis( tert -butyl)methylgallium. In some embodiments, a chemical reactant vessel according to the present disclosure contains bis( tert -butyl)methylindium.

In another aspect, a vapor deposition assembly comprising a reactant vessel according to the present disclosure is disclosed. The vapor deposition assembly comprises a reactant delivery system comprising a reaction chamber for depositing a Group 13 metal containing material on a substrate and a reactant vessel according to the present disclosure coupled to the reaction chamber to react a metal alkyl precursor according to the present disclosure. feed into the chamber.

A vapor deposition assembly for depositing a Group 13 metal-containing material on a substrate, comprising: one or more reaction chambers constructed and arranged to hold a substrate, and configured and arranged to provide a metal alkyl precursor in accordance with the present disclosure in a vapor phase into the reaction chamber a precursor injector system. The vapor deposition assembly further comprises a reactant container constructed and arranged to contain a composition according to the present disclosure, the assembly providing a composition according to the present disclosure to the reaction chamber via a precursor injector system, thereby providing a composition according to the present disclosure onto the substrate. constructed and arranged to deposit a metal-containing material.

In some implementations, the vapor deposition assembly may further include a control processor and software configured to operate the reaction chamber to perform an ALD process. In some implementations, the vapor deposition assembly can further include a control processor and software configured to operate the reaction chamber to perform a CVD process.

detailed description of the drawings

The present disclosure is further illustrated by the following exemplary implementations shown in the drawings. The examples presented herein are not intended to be actual views of any particular material, structure, or device, but are merely schematic representations used to describe implementations of the present disclosure. It will be understood that elements in the drawings are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some elements in the figures may be exaggerated relative to other elements to improve understanding of illustrated implementations of the present disclosure. Structures and elements shown in the drawings may include additional elements and details that may be omitted for clarity.

1 shows a reactant vessel 10 according to the present disclosure. The reactant vessel 10 is made of a suitable vessel material, such as stainless steel, aluminum, copper, nickel, silver, alloys thereof, graphite, boron nitride, a ceramic material, or combinations or mixtures of the foregoing. The reactant vessel 10 material may be a thermally conductive material. The reactant vessel 10 material may be a coating or clad material. The reactant vessel includes a housing 11 defining an interior volume 12 of the reactant vessel 10 . The interior volume 12 is adapted to hold a composition according to the present disclosure.

1 , a reactant vessel 10 contains a composition 16 according to the present disclosure. In the figure, the composition 16 is simply placed in the interior volume 12 of the container 10 . However, various arrangements are known in the art for improving or controlling the volatility of the composition within the reactant vessel. Any such arrangement, such as shelves, channels or compartments, may be used in the reactant vessel 10 according to the present disclosure. Also, depending on the process in which the composition 16 is used, its scale, as well as the size of the precursor container 10 , the degree of loading of the precursor in the reactant container 10 may vary. Accordingly, and in this regard, FIG. 1 is a simplified schematic diagram of possible degrees of loading of composition 16 , wherein greater or lesser amounts may be loaded into precursor container 10 .

The reactant vessel 10 may be coupled to a heating means, such as a heater (eg, a radiant heat lamp or a resistive heater). The heating means heats the reactant vessel 10 to enhance evaporation of the precursor in the reactant vessel 10 . The heating means may be internal or external to the reactant vessel 10 .

The housing 11 of FIG. 1 includes a bottom 111 and a sidewall 112 . In some embodiments, the housing 11 has a substantially circular cylindrical shape. Accordingly, the housing 11 has a circular bottom 111 . However, reactant vessel 10 may have any shape that facilitates uniform carrier gas flow through its interior volume 12 . In some embodiments, the reactant vessel 10 has the shape of a substantially rectangular prism. The shape of the reactant vessel 10 may deviate from the ideal geometry discussed above due to its usefulness, ease of manufacture, and ease of handling. For example, any edges and/or corners may be more rounded, and some sides may be at least partially beveled. In some embodiments, the bottom and sidewalls are indistinguishable. The bottom 111 may be curved. The housing 11 can be constructed in one piece, for example by machining. However, it is possible for the housing 11 to be formed of two or more parts attached to each other in a gas-tight manner. For example, the bottom 111 and the sidewall 112 may be separated.

The size and proportions of the reactant vessel 10 may vary depending on the design choice and application in question, due to the scale of the vapor deposition process. In some embodiments, the height of the reactant vessel 10 is greater than its width. In some embodiments, the height of the reactant vessel 10 is equal to its width. In some embodiments, the height of the reactant vessel 10 is less than its width. In some embodiments, the reactant vessel 10 may have a height-to-width aspect ratio in the range of about 0.5-4, such as 1-2 or 1-3. The height of the reactant vessel 10 is the external measurement of the reactant vessel 10 from the lid 13 to the portion of the housing 11 furthest from the lid 13 . The width of the reactant vessel 10 is the longest measurement across the reactant vessel 10 perpendicular to the height.

The reactant vessel 10 includes a lid 13 for isolating the interior volume 12 from the surrounding atmosphere. The lid 13 may include an inlet 14 for supplying a carrier gas into the reactant vessel 10 . The inlet 14 may include an inlet valve 141 , the inlet 14 being configured to selectively introduce a carrier gas into the interior volume 12 of the reactant vessel 10 when the inlet valve 141 is opened. can be arranged. The lid 13 may include an outlet 15 for supplying carrier gas and vaporized precursor into the reaction chamber of the vapor deposition assembly (not shown). The outlet 15 may include an outlet valve 151 and may be arranged to selectively release a carrier gas containing vaporized precursor into the reaction chamber when the outlet valve 151 is opened. When connected to a vapor deposition assembly, gas lines may extend from the inlet 14 and outlet 15, an isolation valve on the line, and a fitting on the valve, the fitting being connected to the gas flow line of the remainder of the vapor deposition assembly. configured to be connected.

Reactant vessel 10 may include additional features omitted from the figures for clarity. For example, the reactant vessel 10 may include precursor dispensing means to facilitate efficient precursor evaporation. To this end, various precursor holding structures or carrier gas guide arrangements may be present within the interior volume 12 of the reactant vessel 10 . The reactant vessel 10 may include features to prevent solid precursor particles from being entrapped in the carrier gas stream. A variety of filters or other capture structures may be used. Additionally, the inlet 14 and outlet 15, as well as the gas lines extending therefrom, are provided between the reactant vessel 10 and the reaction chamber to prevent reactant vapors from condensing and depositing on any components. It may include a heater for heating the valve and gas line.

2 shows in a schematic manner a vapor deposition assembly 20 including a reactant vessel 231 according to the present disclosure. The deposition assembly 20 may be used to perform a deposition method as described herein to deposit a Group 13 metal containing material on a substrate. In the example shown, the deposition assembly 20 includes one or more reaction chambers 22 , a precursor injector system 23 , a reactant vessel 231 for holding a composition according to the present disclosure, a second reactant vessel 232 , a purge gas a source 233 , an exhaust source 24 , and a controller 25 .

Reaction chamber 22 may include any suitable reaction chamber, such as an ALD or CVD reaction chamber.

Reactant vessel 231 may contain vessels and compositions as described herein, alone or in admixture with one or more carrier (eg, inert) gases. The second reactant vessel 232 may contain the vessel and one or more additional reactants alone or in admixture with one or more carrier gases. The purge gas source 233 may include N ₂ or one or more inert gases such as He or Ar. Although shown as three reactant vessels 231 - 233 , the deposition assembly 20 may include any suitable number of reactant vessels. Reactant vessels 231 - 233 may be coupled to reaction chamber 22 via lines 234 - 236 , each of which may include flow controllers, valves, heaters, and the like. In some embodiments, the composition according to the present disclosure, and/or the second reactant and/or purge gas in the reactant vessel 231 may be heated. In some embodiments, a composition according to the present disclosure is from about 50 °C to about 140 °C, such as from about 70 °C to about 130 °C, such as 60 °C, 80 °C, 90 °C, 100 °C , the reactant vessel 231 is heated to reach 110 °C or 120 °C. The exhaust source 24 may include one or more vacuum pumps.

Controller 25 includes electronic circuitry and software for selectively operating valves, manifolds, heaters, pumps, and other components included in deposition assembly 20 . These circuits and components operate to introduce precursors, reactants, and purge gases from respective sources 231 - 233 . The controller 25 may control the timing of the gas pulse sequence, the temperature of the substrate and/or reaction chamber 22 , the pressure of the reaction chamber 22 , and various other operations to provide proper operation of the deposition assembly 20 . have. The controller 25 may include control software that electrically or pneumatically controls valves for controlling the flow of precursor, reactant and purge gases into and out of the reaction chamber 22 . The controller 25 may include modules, such as software or hardware components, that perform specific tasks.

Other configurations of the deposition assembly 20 are possible that include different numbers and types of precursor and reactant sources and purge gas sources. It will also be appreciated that there are a number of arrangements of valves, conduits, precursor sources, purge gas sources that may be used to achieve the purpose of selectively and interlockingly supplying gas into reaction chamber 22 . Also, while schematically representing the deposition assembly, many components have been omitted for simplicity of illustration, which components may include, for example, various valves, manifolds, purifiers, heaters, vessels, vents, and/or bypasses. may include

During operation of the deposition assembly 20 , a substrate, such as a semiconductor wafer (not shown), is transferred, for example, from a substrate handling system to the reaction chamber 22 . Once the substrate(s) have been transferred to the reaction chamber 22 , one or more gases, such as precursors, reactants, carrier gases, and/or purge gases, are introduced into the reaction chamber 22 from the gas sources 231 - 233 . .

Example

In the example below, the preparation of bis( tert -butyl)methylaluminum is demonstrated on an experimental scale. However, the process may be scalable to large volumes, with variations within the ability of those skilled in the art. For example, filtration can be used to remove the insoluble LiCl salt byproduct prior to distilling the solvent as described in step 3. Then, distillation of the solvent after filtration can be expected to produce the desired tB u ₂ AlMe product in appropriate purity (>95% pure) without complete sublimation.

In the examples below, tBu represents tert-butyl and Me represents methyl.

Example 1 Preparation of bis( tert -butyl)methylaluminum from bismethyl( tert -butyl)aluminum.

Starting materials for t BuAlMe ₂ were prepared as described for use as starting materials in Jones et al., Journal of Crystal Growth, 1989, 96: 769-773. Briefly, the t BuAlMe ₂ synthesis method involves adding tert -butyllithium to a solution of Me ₂ AlCl in a non-polar aliphatic solvent such as hexane. Me ₂ AlCl solution can be purchased from a commercial supplier or prepared by combining AlMe ₃ and AlCl ₃ in a 2 to 1 molar ratio in the same solvent.

The synthesis of bis( tert -butyl)methylaluminum was carried out according to the chemical reaction of Scheme (I).

t Bu ₂ AlMe was prepared using the steps described below. All steps were performed with strict exclusion of oxygen and moisture using standard inert atmosphere techniques.

Step 1: t BuAlMe ₂ with AlCl ₃ are combined in a 1:1 molar ratio

First, 52.6 grams (394 mmol) of AlCl ₃ were placed in a 3 liter round bottom flask equipped with a PTFE-coated magnetic stir bar. 700 mL of anhydrous hexanes was added to the flask and stirring of the resulting suspension was initiated. 45.0 grams (394 mmol) of tBuAlMe ₂ were added to the flask. The mixture was stirred at ambient temperature for one hour to dissolve all AlCl ₃ to give a clear colorless solution.

Step 2: t Addition of BuLi

Cool the contents of the flask using a -78 °C cold water bath and continue stirring. When the temperature of the reaction mixture dropped to -30 °C, a pentane solution of t BuLi (1.69 M, 700 mL, 1.18 mol) was slowly added. The addition was complete over approximately 30 minutes. The mixture was stirred overnight (approximately 18 hours) in a cooling bath, during which time the system gradually warmed to room temperature to complete the reaction.

Step 3: Removal of solvent

The reaction mixture was placed in a heating mantle set to a temperature of 40 °C. While stirring, the reaction solvent was distilled under vacuum controlled to 10 Torr. When the bulk solvent was removed, the vacuum level was reduced to 1 Torr to evaporate the remaining residual solvent. The crude product consisting of a mixture of tBu ₂ AlMe and LiCl was placed in a flask in the form of a white powder.

Step 4: From LiCl salt t Bu ₂ Separation of AlMe.

The crude reaction product from step 3 was transferred to the chamber of the bulk sublimation apparatus. Purified tBuAlMe was collected on the condenser over approximately 6 hours in vacuum at a chamber temperature of 90 °C and a condenser temperature of -20 °C (pressure <100 milliTorr), leaving a non-volatile LiCl by-product in the chamber. 105 grams (876 mmol, 77% yield) of t BuAlMe ₂ (>95% purity) were obtained from the condenser.

Example 2 Preparation of bis( tert -butyl)methylaluminum from trimethylaluminum

Similarly, t Bu2AlMe can be prepared using commercially available reagents AlMe ₃ , AlCl ₃ and t BuLi according to the following reaction scheme (Scheme II). A four-step synthetic process similar to Example 1 can be used, with only the differences recorded for each step compared to that described for Example I.

Step 1: AlMe ₃ and AlCl ₃ are combined in a molar ratio of 1:2

AlMe ₃ (100 mL, 2.0 M in hexanes, 200 mmol) and AlCl ₃ (400 mmol) are combined in a molar ratio of 1:2 and stirred until the system equilibrates.

Step 2: t Addition of BuLi

Add t BuLi (about 1.7 M in hexanes, approx. 700 mL, 1.20 mol) under the same conditions used in the original process described above.

Step 3 and Step 4

The final steps necessary to isolate the product can be completed as in Example 1.

Claims (28)

A composition for depositing a Group 13 metal-containing material on a substrate, the composition comprising a metal alkyl precursor;
wherein the metal alkyl precursor comprises a Group 13 metal atom and two different types of alkyl ligands,
the first ligand type is a branched C4 to C8 alkyl bonded to the Group 13 metal atom through a carbon atom which is bonded to three carbon atoms, the second ligand type is a linear C1 to C4 alkyl, and
wherein the Group 13 metal atom is bound to two ligands of the first ligand type, and wherein the ratio of the first ligand type to the second ligand type in the composition is about 2 to 1. The composition of claim 1 , wherein both ligands of the first ligand type are the same. The composition of claim 1 , wherein the first ligand type is C4 to C6 alkyl. The composition of claim 1 , wherein the first ligand type is tert -butyl. The composition of claim 1 , wherein the second ligand type is methyl or ethyl. The composition of claim 1 , wherein the first ligand type is tert -butyl and the second ligand type is methyl. The composition of claim 1 , wherein the Group 13 metal is selected from the group consisting of aluminum, gallium and indium. The composition of claim 1 , wherein the Group 13 metal is aluminum. The composition of claim 1 , wherein the Group 13 metal is gallium. The composition of claim 1 , wherein the Group 13 metal is indium. The composition of claim 1 , wherein the composition comprises at least 90 w-% of a metal alkyl precursor. The composition of claim 1 , wherein the composition has a vapor pressure of about 1 Torr at a temperature of 64 to 69°C. The composition of claim 1 , wherein the composition is stable for at least 10 weeks at a temperature of 60°C. The composition of claim 1 , wherein the composition is solid at standard temperature and pressure. 15. The composition of claim 14, wherein at least 50% of the metal alkyl precursor is present as a dimer in the solids composition. The composition of claim 1 , wherein the metal alkyl precursor is present as a mixture of dimers and monomers in the gaseous phase. A method for preparing the composition according to claim 1, comprising the step of reacting bis(methyl) tert -butylaluminum with aluminum trichloride and tert -butyllithium to obtain bis(tert-butyl)methylaluminum. , Way. 18. The method of claim 17, wherein bis(methyl) tert -butylaluminum is reacted with aluminum tetrachloride and tert -butyllithium in a molar ratio of about 1:1:3. 18. The method of claim 17, wherein the method comprises purification of bis( tert -butyl)methylaluminum. A process for preparing the composition according to claim 1 , comprising the step of reacting trimethylaluminum with aluminum trichloride and tert-butyllithium to obtain bis( tert -butyl)methylaluminum. A method of depositing a Group 13 metal-containing material on a substrate using a composition comprising a metal alkyl precursor, the metal alkyl precursor comprising a Group 13 metal atom and two different types of alkyl ligands;
the first ligand type is a branched C4 to C8 alkyl bonded to the Group 13 metal atom through a carbon atom which is bonded to three carbon atoms, the second ligand type is a linear C1 to C4 alkyl, and
wherein the Group 13 metal atom is bound to two ligands of the first ligand type, and wherein the ratio of the first ligand type to the second ligand type in the composition is about 2 to 1. 22. The method of claim 21, wherein the Group 13 metal-containing material is deposited by a vapor deposition process. 23. The method of claim 22, wherein the vapor deposition process is a periodic vapor deposition process. 22. The method of claim 21, wherein the Group 13 metal is selected from the group consisting of aluminum, gallium and indium. 1. Use of a composition comprising a metal alkyl precursor, the metal alkyl precursor comprising a Group 13 metal atom and two different types of alkyl ligands;
the first ligand type is a branched C4 to C8 alkyl bonded to the Group 13 metal atom through a carbon atom which is bonded to three carbon atoms, the second ligand type is a linear C1 to C4 alkyl, and
the group 13 metal atom is bound to two ligands of the first ligand type, wherein the ratio of the first ligand type to the second ligand type in the composition is about 2 to 1;
Depositing the Group 13 metal-containing material on a substrate. A reactant vessel containing a composition comprising a metal alkyl precursor, the metal alkyl precursor comprising a Group 13 metal atom and two different types of alkyl ligands;
the first ligand type is a branched C4 to C8 alkyl bonded to the Group 13 metal atom through a carbon atom which is bonded to three carbon atoms, the second ligand type is a linear C1 to C4 alkyl, and
wherein the Group 13 metal atom is bound to two ligands of the first ligand type, and wherein the ratio of the first ligand type to the second ligand type in the composition is about 2 to 1. A vapor deposition assembly for depositing a Group 13 metal containing material onto a substrate, the assembly comprising:
one or more reaction chambers constructed and arranged to hold the substrate;
a precursor injector system constructed and arranged to provide a metal alkyl precursor in a vapor phase into the reaction chamber;
A reactant vessel constructed and arranged to contain a composition according to claim 1, comprising:
wherein the vapor deposition assembly is constructed and arranged to deposit a group 13 metal containing material on the substrate by providing a composition according to claim 1 to the reaction chamber via the precursor injector system. A composition for depositing a carbon-containing material on a substrate, the composition comprising a metal alkyl precursor;
wherein the metal alkyl precursor comprises a Group 13 metal atom and two different types of alkyl ligands,
the first ligand type is a branched C4 to C8 alkyl bonded to said Group 13 metal atom through a carbon atom which is bonded to three carbon atoms, the second ligand type is a linear C1 to C4 alkyl;
wherein the Group 13 metal atom is bound to two ligands of the first ligand type, and wherein the ratio of the first ligand type to the second ligand type in the composition is about 2 to 1.

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